Apparatus for bundling slender articles



Sheet l of' 5 Feb. 18, 1969 w. M. KEIL APPARATUS FOR BUNDLING SLENDER ARTICLES Filed Jan. e, 1967 Feb. 18, 1969 w. M. KEIL APPARATUS FOR BUNDLING SLENDER ARTICLES Sheet 2 of Filed Jan. 6, 1967 zNvENToR. WALTER M. KEN. BY

AUORNE Y Feb. 18, 1969 w. M. Kre-:IL 3,427,959

APPARATUS FOR BUNDLING SLENDER ARTICLES med aan. e. 1967 ATTORNEY United States Patent O 7 Claims ABSTRACT OF THE DISCLOSURE A group of slender articles issupported on a strap which depends from the apex of an arch-shaped support. Tensile forces are applied to the opposite ends of the strap causing the articles to be bundled into a compact, generally circular configuration whereupon the articles are banded. The arch-shaped support preferably comprises a pair of arms which is pivotal between a raised position wherein the upper ends are abutted and define the apex and a lowered position wherein the upper ends are below the level of a conveyor. Groups of the articles are transported along a horizontal path to a position over the strap whereupon the arms are raised and the articles compacted. The compacted articles are then banded and lowered to the conveyor. With the arms in the lowered position, the conveyor transports the banded articles to a discharge station while, simultaneously, a new group of slender articles is conveyed to a position above the strap.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to apparatus for bundling a group of slender articles -prior to being banded, and more particularly to apparatus for bundling a group of articles into a compact, generally circular configuration which is more securely banded.

Description of the prior art In the past, several methods have been employed to strap groups of slender articles, such as pipes, rods and the like. In the most common method, a group of articles is laid across spaced-apart chains. Hoists raise the chains to `suspend the group of articles. When suspended in this manner, the articles arrange themselves into a teardrop configuration and are not very tightly compacted. A banding machine is then employed to apply a metal strap or band about the group of articles. As is conventional, the metal strap or band is placed under considerable tension to retain the articles in a bundle for shipment.

Articles banded in this manner have been known to shift and change position relative to one another during shipment, which results in a loosening of the strap and a deterioration of the bundle. Occasionally, one or more of the slender articles have been caused to slide longitudinally of the bundle during shipment, especially when such bundles are shipped by trucks. The articles become loose because, initially, the articles are arranged in a loosely compacted, teardrop configuration. Consequently, the articles are more or less free to move. The band, even though under considerable tension, cannot maintain the articles in the initial teardrop configuration when the articles are subjected to the vibrations and rough handling encountered during loading, shipment and unloading.

Aside from the foregoing, the prior art method requires considerable manual labor in laying down chains and, after the load has been placed on the chains, manually hooking the chain ends to a hoist.

ICC

SUMMARY OP THE INVENTION As an overall object, the present invention seeks to provide apparatus for bundling a group of slender articles into a compact, generally circular configuration for strapping.

Another object of the present invention is to provide bundling apparatus wherein the top of the group of slender articles being bundled is always at a preselected level whereby, regardless of the outerl diameter of the bundle, overhead strapping machines can be lowered without variation to a preselected position relative to the aforesaid level for strapping the group of articles.

Still another object ofthe present invention is to provide bundling apparatus wherein the group of articles may be rocked in a seesaw fashion causing the articles to roll and become more compacted prior to being strapped.

A further object of the present invention is to provide bundling apparatus incorporating a bundling strap adapted to envelop and support a group of articles and capable of compacting the articles into a generally circular configuration by the application of tensile forces to the ends of said bundling strap.

Still a further object of the present invention is to provide bundling apparatus incorporating a bundling strap capable of being positioned below the horizontal pass line of a conveyor whereby groups of articles may lbe transported horizontally from a loading station to the bundling apparatus and then to discharge.

ln accordance with the present invention, apparatus is provided for bundling a group of slender articles into a generally circular configuration for strapping. The present bundling apparatus comprises a support having an apex and a horizontal opening through which the slender articles extend. A bundling strap includes an intermediate loop depending from the apex into the horizontal opening and supports the group of slender articles. 'Ille bundling strap also includes rst and second strap ends supportingly engaged with the apex and closely adjacent to each other. Means is provided for applying tensile forces to the first and second strap ends to reduce the circumferential length of the intermediate loop whereby the group of slender articles is compacted into a generally circular configuration particularly suited for strapping.

The apex of the support is provided with spaced vertical openings and has a lower face extending between the spaced vertical openings. The first and second strap ends extend upwardly through the vertical openings. The overall arrangement is such that when tensile forces are applied to the first and second strap ends, the group of slender articles is elevated into engagement with the lower face. The lower face thus serves as a means for positioning the top of the group of slender articles at a preselected elevation regardless of the outer diameter of the group of slender articles, as determined by the number of slender articles in the group. Consequently, strapping machinery suspended above the compacted slender articles, may be lowered without variation to a preselected position relative to the lower face for strapping the group of compacted slender articles.

In accordance -with one embodiment of the present invention, the su-pport comprises a pair of arms having lower ends pivotally supported on a base for rotation about axes normal to the arms and upper ends. Means is provided for pivoting the arms in unison and in opposite directions between a raised position wherein the upper ends are abutted and define the aforesaid apex and a lowered position which is below, for example, the hori zontal pass line of the conveyor. The conveyor extends horizontally and includes a loading station and an unloading station which is laterally spaced from the bundling apparatus and positioned on opposite sides thereof. The

arrangement is such that a group of articles may be deposited on the conveyor at the loading station whereupon the group of articles is transported along a horizontal path of travel to a position above the bundling apparatus. The pair of arms is pivoted to the raised position and tensile forces are applied to the bundling strap for compacting the group of articles into a generally circular configuration. The articles are then strapped, after which the strapped articles are lowered to the conveyor. The arms are then lowered, whereupon the conveyor is activated and the group of strapped articles is transported along a horizontal path of travel to the discharge station.

In accordance with an alternative embodiment of the present invention, the support comprises a first arm rigidly secured to a base and extending upwardly therefrom and terminating in a horizontal upper arm portion. A second arm is provided having an upper end and a lower end which is pivotally connected to the base for pivotal movement about an axis nomal to the second arlm. Means is provided for pivoting the second arm between a lowered position wherein the upper end thereof is below the level of the horizontal arm portion and a raised position wherein the upper end abuts the horizontal arm portion and cooperates therewith to define the apex. In this arrangement, a group of articles may be transported along la horizontal path of travel over the second arm and stopped at a position above the bundling apparatus. The second arrn is then raised and tensile forces are applied to the bundling strap, whereupon the group of articles is raised into abutment with the lower surface and compacted into a generally circular configuration. Alternatively, the second arm may be pivoted into an inclined position wherein the bundling strap extends from the upper end thereof toward the horizontal arm portion of the first arm. A group of articles may be transported, for example, by means of hoists, from either side of the apparatus and deposited on the bundling strap. Thereafter, the second arm is pivoted to the raised position and tensile forces are applied to the bundling strap causing the group of articles to be compacted into `a generally circular configuration.

DESCRIPTION OF THE DRAWINGS FIG. 4 is a fragmentary cross-sectional view illustrating means for locking a pair of arms in a raised position; and

FIGS. 5 and 6 are cross-sectional views, similar to FIG. 3, illustrating alternative embodiments of the present bundling apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT General description Referring now to FIGS. 1 and 2, there are illustrated platforms supporting a number of bundling apparatus 12 which are spaced along the length thereof. Adjacent to each bundling apparatus 12 and supported by additional platforms 11 is a horizontal conveyor 14 which, as can be seen in FIG. 2, is adapted to convey slender articles along a horizontal pass line indicated by the dashdot line 16. The conveyor 14 includes a loading station 18 and an unloading station 20, both of which are laterally spaced from the bundling apparatus 12 and are positioned on opposite sides thereof. The conveyor 14 includes a plurality of carrier members 22 spaced along the length thereof and arranged to be positioned sequentially at the loading station 18, above the bundling apparatus 12 and the unloading station 20.

As shown in FIG. 2, a conventional strapping machine 24 is sus-pended from structural steel 26 and includes a hoist 28 operable to raise and lower the strapping machine 24. The strapping machine 24 is of conventional design and serves to apply a metal strap about a group of slender articles to secure the articles in a rigid bundle. A plurality of the strapping machines 24 are positioned adjacent to each of the bundling apparatus 12. Each of the strapping machines 24 is schematically indicated in FIG. l by the center line labeled 24.

Referring still to FIG. l, groups of slender articles are schematically illustrate by the dash-dot outlines labeled A, B, C and D. The width of these groups is indicative of their outer diameter. The present bundling apparatus 12 is capable of bundling groups of slender articles having a maximum diameter as illustrated by the group A and a minimum diameter as illustrated by the group D. Groups of slender articles having dimensions intermediate the maximum and minimum diameters are schematically represented by the groups B and C. It is to be noted in FIG. l that the tops of the groups A, B, C and D are at the same level regardless of the outer diameter of the group. Therefore, the strapping machine 24 can be lowered without variation to a preselected position for strapping of the bundle.

From the foregoing general description, it should be readily apparent that strapping of groups of slender articles may be carried out automatically. For example, a group of slender articles is deposited on the horizontal conveyor at the loading station 18, and the conveyor is activated to transfer the group of articles to a position above the bundling apparatus 12. The bundling apparatus 12 is then activated to compact the group of articles into a generally circular configuration in a manner which Will hereinafter be more fully described. At this time, the strapping machine 24 is automatically lowered to the preselected position, whereupon the `group of articles is strapped into a rigid bundle. The bundling apparatus 12 then lowers the strapped articles to the conveyor 14. Thereafter, the bundling apparatus arms unlock and rotate outwardly until they are below conveyor 14, whereupon the conveyor 14 is activated to transfer the group of strapped articles to the unloading station 20. At this point, the bundle is inspected and then discharged from the conveyor.

BUNDLING APPARATUS 12 The preferred embodiment of the present bundling apparatus 12 is illustrated in FIGS. 2, 3 and 4.

Referring in particular to FIG. 3, the present bundling apparatus 12 comprises, in general, a support 30 having an apex 32 and a horizontal opening 34 through which a group of slender articles schematically illustrated at 36, extends. The apparatus 12 further includes a bundling strap 38 including an intermediate loop 40 and first and second strap ends 42, 44. The apex 32 is provided with spaced openings 46 receiving the first and second strap ends 42, 44. The rst and second strap ends 42, 44 are supportingly engaged on pulley means 48 carried at the apex 32. Means, preferably in the form of fluid operated cylinders 50, are provided for applying tensile forces to the first and second ends 42, 44. The apex 32 includes a lower face 52 which extends between the spaced openings 46.

As illustrated in FIG. 3, the group of slender articles 36 is compacted into a generally circular configuration by the bundling strap 38 when tensile forces are applied to the first and second ends 42, 44. That is to say, when tensile forces are applied, the first and second strap ends 42, 44 are pulled over the pulley means 48, causing a reduction in the circumferential length of the bundling strap 38 and also vcausing the slender articles 36 to be elevated into engagement with the lower face 52. The group of slender articles 36 are compacted into a generally circular configuration.

Referring now to FIGS. 2 and 3, the support 30 preferably comprises a pair of arms 54, 56 having upper ends 58, 60 and lower ends 62, 64. The lower ends 62, 64 are secured to spaced shafts 66, which, in turn, are rotatably supported on a base 68- for rotation about the central axes of the shafts 66 which are normal to the arms 54, 56.

Means 70 is provided for pivoting the arms 54, 56 about the shafts 66. The pivoting means 70 comprises, in effect, a rack and pinion arrangement. The lower ends 62, 64 are provided with teeth which define a pinion 72. A rack 74 is positioned between and meshes with the pinions 72. The rack 74 is forcibly raised and lowered along a vertical path of travel by a fluid operated cylinder 76.

As will be appreciated by inspection of FIGS. 2 and 3, the pivoting means 70 is operable to pivot the arms 54, 56 between a raised position, shown in FIG. 3, wherein the upper ends 58, 60 are abutted and dene the apex 32; and a lowered position as shown in FIG. 2 wherein the upper ends 58, 60 are below the horizontal pass line 16 of the conveyor 14.

It will be noted in FIGS. 2 and 3 that the base 68 has an upper surface 78 which is likewise below the horizontal pass line 16 of the conveyor 14. When the arms 54, 56 are in the lowered position, as illustrated in FIG. 2, the bundling strap 38 extends from the upper end 60 Iover the upper surface 78 to the upper end 58. The bundling strap 38 is likewise entirely below the horizontal pass line 16. Accordingly, when the arms 54, 56 are pivoted to the raised position illustrated in FIG. 3, the bundling strap 38 envelops the group of slender articles 36. When tensile forces are applied to the strap ends 42, 44, the group of articles 36 is lifted from the carrier 22 upwardly into engagement with the lower surface 52 of the apex. After the group of articles 36 has been compacted and strapped, they are lowered back to the carrier 22 for conveyance to the unloading station.

Referring again to FIG. 3, each of the fluid operated motor means 50 preferably comprises a conventional telescoping Huid operated cylinder having a stationary sleeve 80 pivotally connected to the arms 54, 56 at 81 and two telescoping sleeves 82, 84. A piston rod 86 is carried by the second telescoping sleeve 84. A yoke 88 is carried at the extreme end of the piston rod 86 and supports a sprocket 90 engaging the bundling strap 38. The yoke 88 carries rollers 91 which engage a slot 92 formed in the arms 54, 56. The sprocket 90 is guided by the rollers 91 engaging the slot 92.

By comparing FIGS. 2 and 3, it will be seen that the iluid operated motor means S0 is in a compact collapsed condition when the arms 54, 56 are in the lowered position (FIG. 2); and when the arms 54, 56 are in the raised position (FIG. 3), the fluid operated motor means 50 is telescopically extended to apply tensile forces to the opposite ends 42, 44 of the bundling strap 38. In FIG. 3, the motor means 50 are illustrated in their extreme extended position and are employed to compact the group of slender articles 36 which is of minimum size. The bundling strap 38 is also shown in dotted outline to illustrate the bundling of a group of the slender articles having a maximum diameter. When bundling a maximum size group of articles, the motor means 50 will, of course, be extended only a short distance rather than the maximum distance illustrated in FIG. 3.

It is also to be noted at this time that one of the motor means 50 may be sequentially extended and retracted during a bundling operation. This action causes the articles to rock and orient themselves in the most compact conguration. Subsequent strapping of the thus-compacted slender articles results in a rigid bundle less likely to deteriorate in the manner described above.

In the present bundling apparatus 12, the bundling strap 38 preferably comprises a roller drive chain. In this connection, the pulley means 48 comprise sprockets which are engaged by the drive chain 38. The chain 38 passes over the sprockets 48 around the sprockets 90 associated with the motor means 50 and. up along the arms 54, 56 to points of rigid connection indicated at 94.

Inasmuch as considerable tensile forces are applied to the bundling strap 38, means must be provided for releasably connecting the upper ends 58, 60 to prevent separation of the arms 54, 56. In this connection, reference is directed to FIG. 4 wherein the releasable connecting means is shown comprising a hook rotatable about a shaft 96, which also carries one of the sprockets 48. The hook 95 is connected to a lever arm '98 which, in turn,- is pivotally connected to a iluid operated cylinder likewise pivotally connected to the upper end 60 by a yoke 102. The hook 95 is engaged over a rib 104 formed in the upper ends 58, 60. Activation of the fluid operated cylinder 100 causes the lever arm 98 to rotate in a counterclockwise direction, thereby lifting the hook 95 into the dotted line position illustrated in FIG. 4. The arms 54, 56 are thus released and may be pivoted to the lower position.

ALTERNATIVE EMBODIMENTS Alternative embodiments of the present bundling apparatus are illustrated in FIGS. 5 and 6. Corresponding numerals will be employed to identify corresponding parts heretofore described.

In FIG. 5, there is illustrated bundling apparatus 114 comprising a support 30" having an apex 32' and a central opening 34. The support 30 comprises a rfirst arm 116 rigidly supported on a base 118 and extending thereabove. The first arm 116 terminates in a horizontal upper arm portion 120 and carries the fluid operated motor means 50. The support -30 additionally includes a second arm 122 having an upper end 124 and a lower end 126. The lower end is secured to the shaft 66 which, in turn, is rotatably supported on the base 118. Means 70 is provided for pivoting the second arm 122. The pivoting means 70` preferably comprises the pinion 72 formed on the lower end 126 and the rack 74 secured to and movable by the fluid operated imotor means 76.

The pivoting means 70 is operable to pivot the second arm 122 from a raised position, indicated in full lines, wherein the upper end 124 abuts the horizontal arm portion 120 and cooperates therewith toV define the apex 32'; and a lowered position wherein the upper end 124 is below the level of a discharge conveyor 128; and an intermediate inclined position indicated at 130. The second arm 122 is retained in the inclined position by an arm lock mechanism 132. The mechanism 132 may comprise a pin 134 which is insertable into a recess 136 formed at a level in the rack 74. The arm lock mechanismy 132 is operable by conventional and automatic means not illustrated herein.

The bundling strap 38 again comprises a roller drive chain having a first strap end 138 rigidly secured to the upper end 124 of the second arm 122. The opposite end of the bundling strap 38 extends over a sprocket 48 carried by the horizontal arm portion 120i, then around the sprocket 90 associated with the fluid operated motor means 50 and then to the point of rigid connection 94.

In operation, the second arm 122 is pivoted to the inclined position wherein the bundling strap 38 is suspended between the upper end 124 and the sprocket 48 in the manner illustrated by the dash-dot center line 38a. A group of slender articles is deposited on the bundling strap 38 from either side of the apparatus 114. During deposition of the slender articles, the motor means 50 is activated to lower the bundling strap, ifor example, to the position indicated by the dash-dot center line at 38h wherein the entire group of slender articles is supported thereby. The motor means 50 may be sequentially extended and contracted to cause compaction of the articles as explained above. Thereafter, the pivoting means 70 is activated to pivot the second arm 122 into the raised position. At this time, the motor means 50 is activated to apply tensile forces to the bundling strap 38 such that the group of articles is compacted into a generally circular configuration. Straps are then applied to the articles whereupon the strapped articles are lowered to a carrier 140 supported on the conveyor 128. The second arm 122 is then lowered to the lower position whereupon the conveyor 128 transports the strapped articles along a horizontal path of travel to discharge.

Referring now to FIG. 6, there is illustrated a further alternative embodiment of the present bundling apparatus, indicated generally by the numeral 150. The apparatus 150 comprises a support 30" having an apex 32" and a horizontal opening 34". The support 30 comprises a base 152 having a first arm portion 154 formed ntegrally therewith and extending thereabove. The first arm 154 terminates in a horizontal arm portion 156 which, in turn, carries the sprocket 48. The support 36" additionally includes a second arm 158 having an upper end 160 positioned to abut the horizontal arm portion 156 and cooperating therewith to define the apex 32". The second arm 158 additionally includes a lower en'd 162` secured to a shaft 164 which, in turn, is pivotal on journals 166. The shaft 164 is driven -by motor means schematically illustrated at 168, to pivot the second ar-m 158 between the raised position wherein the upper end 160 abuts the horizontal arm 156 and a lowered position wherein the upper end 160 is below the level of a discharge conveyor 128. The second arm 158 is also positionable at an intermediate inclined position indicated at 170` between the raised position and the lowered position.

In this embodiment, the bundling strap 38 again comprises a roller drive chain having a first strap end 172 rigidly secured to the upper end 160. The opposite end of the bundling strap extends over the sprocket 48 to a drive sprocket 174 carried on the drive shaft 176 journaled to the yfirst arm 154. The bundling strap extends from the drive sprocket 174 over an idler sprocket 178 beneath a pulley 180 and has a remote opposite end 182 rigidly secured to the first arm 154. The pulley 180 is connected to a weight 184 which serves to take up any slack in the bundling strap 38. The drive shaft 176 and, hence, the ydrive sprocket 174 are driven by motor means schematically illustrated at 186.

Operation of the bundling apparatus 150 and 114 is similar with the exception that in the bundling apparatus 150, motor means 186 is employed to forcefully rotate the drive sprocket 174 and, hence, pull or loosen the bundling strap 38, as desired.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in for-m and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.

I claim as my invention:

1. In apparatus for bundling a group of slender articles into a generally circular configuration for banding, the combination comprising:

a support having a horizontal opening through which said slender articles extend and an apex, said support comprising a base having an upper surface;

a'pair of spaced arms projecting upwardly of said upper surface, said arms having upper ends which may be abutted to define said apex;

means for pivotally connecting at least one of said arms to said base for rotation about an axis normal to said arms; and

means for pivoting said one of said arms between a raised position wherein said upper ends are abutted and a lowered position wherein said 4upper ends are spaced from each other;

a bundling strap including an intermediate loop depending from said apex into said horizontal opening and supporting said group of slender articles, and first and second strap ends supportingly engaged by said apex and -closely adjacent to each other; and

means for applying tensile forces to said strap ends to reduce the circumferential length of said intermediate loop, thereby compressing said group of slender articles into a -generally circular configuration;

said combination being characterized by including means for releasably connecting said upper ends when abutted, to prevent separation of said arms when tensile forces are applied.

2. In apparatus for bundling a group of slender articles into a generally circular configuration for banding, the combination comprising:

a support having a horizontal opening through which said slender articles extend and an apex, said support comprising a base having an upper surface;

a pair of spaced arms having upper and lower ends;

means for pivotally connecting said lower ends to said base for rotation about spaced parallel axes normal to said arms; and

means for pivoting said arms in unison and in opposite directions between a lowered position wherein said upper ends are below the level of said upper surface and a raised position wherein said upper ends are abutted and define said apex;

a bundling strap including an intermediate loop depending from said apex into said horizontal opening and supporting said group of slender articles, and first and second strap ends supportingly engaged by said apex and closely adjacent to each other;

means for applying tensile forces to said strap ends to reduce the circumferential length of said intermediate loop, thereby compressing said group of slender articles into a generally circular configuration; and

conveyor means for transporting a group of slender articles along a horizontal path to ia position directly above said upper surface;

said arms being in said lowered position and said bundling strap extending from one of said upper ends, over said upper surface to the other of said upper ends, whereby when said arms are pivoted upwardly to said raised position, said bundling strap surrounds said group of slender articles and lifts the same from said conveyor means.

3. The apparatus defined in claim 2 wherein said conveyor means includes a loading station at which groups of slender articles are deposited on said conveyor means and an unloading station at which said group of slender articles are discharged after being banded; said loading station and said unloading station being laterally spaced from said bundling apparatus and positioned on opposite sides thereof.

4. In apparatus for bundling a group of slender articles into a generally circular configuration for banding, the combination comprising:

a support having a horizontal opening through which said slender articles extend and an apex; said support comprising a base;

a first arm rigidly secured to said base and extending upwardly therefrom, said first arm terminating in a yhorizontal upper arm portion which comprises part of said apex;

a second arm having an upper end and a lower end;

means for pivotally connecting said lower end to said base for pivotal movement about an axis normal to said second arm; and

means for pivoting said second arm between a lowered position wherein said upper end is below the level of said horizontal arm portion and a raised position wherein said upper end abuts said horizontal arm portion;

a bundling strap including an intermediate loop depending from said apex into said horizontal opening and supporting said group of slender articles, and rst and second strap ends supportingly engaged by said apex and closely adjacent to each other; and

means for applying tensile forces to said strap ends to reduce the circumferential length of said intermediate loop, thereby compressing said group of slender articles into a -generally circular configuration.

5. The apparatus dened in claim 4 wherein said bundling strap has said rst strap end thereof secured to said upper end of said second arm and extends therefrom to said horizontal upper arm portion of said rst arm; and including conveyor means for depositing a -group of slender articles on said bundling strap when said second arm is in said lowered position.

6. The apparatus deined in claim 5 -wherein said means for applying tensile forces comprises:

motor means connected to said second strap end, said motor means being reversible and operable to increase and decrease the circumferential length of said intermediate loop, whereby said group of slender articles is rocked and compacted in a closely nested relation prior to the application of said tensile forces.

7. In apparatus for bundling a group of slender articles into a generally circular conguration for banding, the combination comprising:

a support having a horizontal opening through which said slender articles extend and an apex;

a bundling strap including an intermediate loop depending from said apex into said horizontal opening and supporting said group of slender articles, and rst and second strap ends supportingly engaged by said apex and closely adjacent to each other; and

means for applying tensile forces to said strap ends to reduce the circumferential length of said intermediate loop, thereby compressing said group of slender articles into a generally circular configuration, said means for applying tensile torces comprising a pair of oppositely acting motor means, one positioned on each side of said apex, each of said motor means being connected to one of said strap ends and serving to pull said strap ends in opposite directions.

References Cited UNITED STATES PATENTS 987,740 3/ 1911 Peterman 10G-212 2,425,430 8/ 1947 Heaton et al. 10G-212 XR 2,992,606 7/ 1961 Trachtman et al. 100-212 FOREIGN PATENTS 557,171 4/1923 France. 167,343 5/ 1934 Switzerland.

30 BILLY J. WILHITE, Primary Examiner. 

